1. Field of the Invention
The present invention relates generally to read head portions of magnetic heads for hard disk drives, and more particularly to read heads having a reactive ion etch (RIE) defined read width.
2. Description of the Prior Art
One well known way to improve the performance of hard disk drives is to increase the areal data storage density of the magnetic hard disk. This can be accomplished by reducing a written data track width, such that more tracks per inch can be written on the disk. To read data from a disk with the reduced track width, it is also necessary to develop a sufficiently narrow read head having a narrow read width, such that unwanted magnetic field interference from adjacent data tracks is substantially eliminated.
The standard prior art read head includes a plurality of thin films that are deposited and fabricated to produce a giant magnetoresistance (GMR) read head, as is known to those skilled in the art. In a commonly used GMR read head, as shown in FIG. 3 and described in detail herebelow, a GMR read sensor is located in a read region, while a longitudinal bias (LB) stack and a conductor are located in each of two side regions. The GMR read sensor typically comprises Al2O3/NiCrFe/NiFe seed layers, an antiferromagnetic PtMn transverse pinning layer, a ferromagnetic CoFe keeper layer, a nonmagnetic Ru spacer layer, a ferromagnetic CoFe reference layer, a nonmagnetic CuO spacer layer, a ferromagnetic CoFe sense layer, and nonmagnetic Cu/Ta cap layers. The LB stack used for hard-magnetic stabilization of the GMR read sensor typically comprises a nonmagnetic Cr film and a hard-magnetic CoPtCr film. Alternatively, the LB stack used for antiferromagnetic stabilization of the GMR sensor may typically comprise a ferromagnetic CoFe film and an antiferromagnetic Ir—Mn film. The conductor typically comprises nonmagnetic Ta/Rh/Ta films.
In the typical fabrication process of the prior art GMR read head, the GMR read sensor is deposited, and bilayer photoresists are then applied and exposed to mask the GMR read sensor in a read region for defining a read sensor width. The unmasked GMR sensor in side regions is removed by ion milling. The LB stack is then deposited at the sensor edges in the unmasked side regions, and the bilayer photoresists are subsequently removed. Due to shadowing effects of the bilayer photoresists it is difficult to achieve a designed read width, and sensor instability often results. This is because both the GMR read sensor and the LB stack are tapered and abutted with each other at the sensor edge, and due to the shadowing effects, the boundary between the read region and the side regions is ambiguous, so that the designed read width cannot easily be attained.
In the present invention, the read width is defined by RE before the bilayer photoresist is applied. As a result, the read width is accurately defined and improved device performance results.